CCDE 400-007-en-unlocked.pdf

### CCDE 400-007: Key Knowledge Points and Considerations #### Overview The document "CCDE 400-007-en-unlocked.pdf" provides insights into the Cisco Certified Design Expert (CCDE) certification, focusing on key aspects of designing robust network architectures. This includes understanding the critical elements of disaster recovery and data replication strategies. The document outlines specific scenarios and questions related to data center design, highlighting the importance of meeting Recovery Point Objectives (RPOs) and Recovery Time Objectives (RTOs). #### Key Knowledge Points **1. Data Center Site Deployment** - **Primary and Secondary Sites:** The deployment involves setting up primary and secondary data center sites, each equipped with redundant Storage Area Networks (SANs). - **Data Protection:** There is an expectation for data protection between the data center sites, which are located approximately 100 miles (160 km) apart. - **Target RPO/RTO:** The targeted RPO is 3 hours, and the RTO is 24 hours. **2. Replication Considerations** - **Distance Impact:** The distance between the sites can introduce one-way delay, affecting the ability to meet the specified RPO and RTO. - **VSAN Extension:** VSANs (Virtual SANs) should be extended from the primary to the secondary site to improve performance and availability. - **Fault Isolation:** Routing VSANs between sites helps to isolate fault domains and increase overall availability. - **Replication Type:** Synchronous data replication might be necessary to meet the business requirements, while asynchronous replication could be used to avoid performance impact on the primary site. **3. Business Requirements and Replication Method** - **Business Requirement:** The Chief Technology Officer (CTO) requires the RTO and RPO for a new system to be as close as possible to zero. - **Replication Method:** Synchronous replication over geographically dispersed dual data centers via MPLS is a suitable approach to meet these requirements. #### Detailed Explanation **Understanding RPO and RTO** - **Recovery Point Objective (RPO):** This refers to the maximum acceptable amount of data loss measured in time. In the given scenario, the RPO is set at 3 hours, indicating that no more than 3 hours' worth of data can be lost during a disaster recovery event. - **Recovery Time Objective (RTO):** This is the maximum acceptable downtime before a system must be restored to normal operation. Here, the RTO is 24 hours, meaning that the system should be back online within 24 hours after a failure. **VSAN Extension** - **Enhancing Performance and Availability:** Extending VSANs from the primary to the secondary site improves performance by ensuring that both sites share the same virtual fabric. This allows for seamless communication and reduces latency. - **Isolating Fault Domains:** By routing VSANs between sites, the architecture can better handle failures. If a problem occurs in one site's VSAN, it does not affect the other site, thus increasing overall availability. **Choosing Replication Type** - **Synchronous vs. Asynchronous Replication:** - **Synchronous Replication:** This type of replication ensures that data is immediately written to both the primary and secondary sites. It is ideal for achieving near-zero RPO but may impact the performance of the primary site due to increased latency. - **Asynchronous Replication:** This method allows data to be replicated at regular intervals, reducing the performance impact on the primary site. However, it introduces a risk of data loss as the data is not instantly available on the secondary site. **Geographically Dispersed Dual Data Centers** - **MPLS (Multiprotocol Label Switching):** Using MPLS for connecting geographically dispersed dual data centers ensures high bandwidth and low latency, making it suitable for synchronous replication. This method helps in maintaining the integrity of data across sites while minimizing data loss and downtime. **Conclusion** In summary, designing a resilient and efficient data center infrastructure involves careful consideration of various factors such as RPO/RTO requirements, VSAN extension, and the choice of replication methods. Understanding the nuances of these elements is crucial for architects aiming to achieve high availability and minimal data loss in their systems.